External Drive that runs Windows

Discussion in 'Windows, Linux & Others on the Mac' started by falcon1315, Oct 31, 2015.

  1. falcon1315 macrumors newbie

    Joined:
    Oct 31, 2015
    #1
    I am trying to make an external drive that runs Windows. I know I can use Bootcamp or Parallel to have it on the machine, but I am trying to have the OS on the Macbook itself. Is this possible? If so, how would I go about doing it? And what do I need?

    The computer is a Macbook Pro - Retina, early 2015, running El Capitan.

    Thank you.
     
  2. austinpike macrumors 6502

    Joined:
    Oct 5, 2008
    Location:
    MN
    #2
    Not sure if you mistyped something there...? If your goal is to boot windows from an external, get a thunderbolt drive. Windows installer will see it as SATA and it is pretty straightforward. There are ways to do it with a usb external but it is kind of convoluted - check the windows/other OS forum on here, there are a number of threads.
     
  3. falcon1315 thread starter macrumors newbie

    Joined:
    Oct 31, 2015
    #3
    I did mistype something, sorry about that. Should say " I am trying to not have the OS on the Macbook itself". But thunderbolt drive, got it. I don't need a virtual machine or anything like that? Is it just a matter of running the Windows installer?
     
  4. austinpike macrumors 6502

    Joined:
    Oct 5, 2008
    Location:
    MN
    #4
    I set up my nMP at work to use Win8 on a external (Seagate TB GoFlex sled w/ naked SSD)... It's been awhile and I don't recall the exact process. I definitely didn't use a virtual machine, winclone, or anything.

    Make sure you use Win8 or 10; Win7 doesn't include USB3 drivers and that keeps you from completing the install as your keyboard and trackpad won't work.

    I'd make sure you have your internal drive backed up and be prepared for some trial and error. Sorry I can't be of more help than that...
     
  5. dirtydeeds98 macrumors newbie

    Joined:
    Nov 1, 2015
    #5
    You can use a program called WintoUSB to install Windows to external USB drive, (USB3 only works with Win 8/8.1/10), and then just use the Option key to boot into the external drive but you will need Windows to run this app to setup the external drive first. This might be a catch-22 for you. Do you have access to Windows PC? I think a VM might be able to work temporarly to setup the external drive. Best if you use a SSD.
     
  6. supermariofan25, Nov 6, 2015
    Last edited: Nov 6, 2015

    supermariofan25 macrumors regular

    supermariofan25

    Joined:
    Feb 7, 2011
    #6
    One way that I can think of is to download VirtualBox and use the VBoxManage rawdisk command to mount the external drive as a SATA HD to the VM instead of it being seen as a USB drive it that makes any sense. Make sure to boot the VM in EFI so that the drive will be bootable when done. For details on how to use the VBoxManage commands look in the Virtual Box user manual. I will also be posting a basic guide down bellow.
     
  7. supermariofan25 macrumors regular

    supermariofan25

    Joined:
    Feb 7, 2011
    #7
    ***DISCLAIMER*** I have not tested this method my self, therefore I highly recommend that you backup your internal hard drive to prevent data loss and continue at your own risk ***DISCLAIMER***

    To install Windows to an external hard drive using VirtualBox you may use the following as a guide.

    To create a Virtualbox 'RAW disk VMDK' to attach a physical drive to a virtual machine you will first need to have VirtualBox installed of course.

    Next open Disk Utility with your desired disk attached and find the BSD device node of the drive by looking in the drives 'Info' window and looking for something like 'disk1' or '/dev/disk1'.

    Once you know what the BSD device node is, unmount each partition on the drive without ejecting the drive fully otherwise it will disappear from Disk Utility. The partitions must be unmounted otherwise the following command will not work.

    Open a new terminal window and type (without quotes) 'sudo VBoxManage internalcommands createrawvmname /Users/username/Desktop/USB.vmdk -rawdisk /dev/diskX', this will make a file called USB.vmdk on your desktop with instructions for VirtualBox to mount the desired disk inside the virtual machine. Make sure that you replace /username/ with your username and /diskX with the device node of the desired drive (e.g. /dev/disk1)

    For some odd reason I have found that VirtualBox doesn't have permission to use the file you just created, so instead we must start VirtualBox using sudo in the Terminal by issuing the command 'sudo VirtualBox', this will open VirtualBox as root where the file can be used without any issues, Create a new VM using the desired settings but leave the hard drive empty for now. In the setting under 'System' make sure that 'Enable EFI', 'Enable I/O APIC' 'Enable VT-x/AMD-V' and 'Enable PAE/NX' are all checked and that the Virtual Machine is a 64 Bit Virtual Machine.

    You will have noticed that after issuing the VBoxMange command earlier OS X re-mounted the drive, you will then need to re-open Disk Utility to unmount all the partitions of said drive before you can attach the USB.vmdk file to the VirtualBox, once the drives partitions have been unmounted you may attach the .vmdk file to the Vm by opening Settings - Storage then clicking the little 'Add Hard Drive' icon on the SATA controller. Once the file has been attached OS X may re-mount the drive once again so it would be handy to keep Disk utility open to unmount the drive again.

    Once you have successfully attached the drive to the virtual machine you can attach a Windows ISO to the empty optical drive in the Storage tab and boot the Virtual Machine, Install Windows as usual completely erasing the drive and letting Windows do the rest. Once windows has done the initial install from the iso file you can then close Virtualbox and reboot your Mac to the external drive to continue the installation of Windows.
     

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